D. 11. Browne — Phosphorus in Iron Mtn., Mich. 303 



In sinking a winze in No. 1 Eoom, 5 Shaft, 5£ Level, the 

 following facts were noticed. The drift running east from the 

 winze showed ore running from *015 phosphorus to *030 ; the 

 winze as sunk passed through ore running from '015 to '029. 

 Lines drawn from the point in the drift where a certain per- 

 centage of phosphorus was noticed to a corresponding point in 

 the winze showed an angle of about 15° with the horizon. 

 Also in sinking a winze in No. 2 R., 5 Sh., 5^ Level, similar 

 lines of equal chemical composition were noticed. (See fig. 

 20.) In sinking 5 shaft from the 7th to the 8th Level, and in 

 sinking the winzes in No. 1 and No. 2 Rooms it was noticed 

 that the winzes passed through ore previously met with in 

 drifts and winzes to the east. These isochemic lines will be 

 easily seen in figure 21. If now we take a small vein as that 

 composing No. 1 and No. 5 Rooms, A shaft, 6 Level, and at- 

 tempt to outline the isochemic lines in the plane of the winzes 

 the regularity is at once patent. On the entry the first-class 

 ore was confined to the last set west in the room. As the room 

 stoped up, this first-class ore was thrown more to the center of 

 the room. The course of the isochemic lines is very plainly 

 indicated by the average analyses marked in the map of this 

 room. (Fig. 18.) The first-class ore continues steadily along the 

 western boundary of the room, and the high phosphorus ore as 

 steadily follows the course of rock to the east. A winze sunk 

 in the room showed all the changes from low to high phos- 

 phorus, previously met with east of the winze in the entry. 

 Analyses taken from a small and very characteristic lens of 

 ore forming No. 4 Room, 1 Shaft, 6 Level, shows very clearly 

 the tendency of isochemic lines to run in the same direction 

 as the pitch of the ore, and also the tendency of phosphorus 

 to increase toward the upper part of the deposit. (Figs. 10 

 and 11.) 



In attempting to draw up a vertical longitudinal section of 

 the western end of the deposit, the principal difficulty lay in 

 reducing so many analyses to the same plane. In consequence 

 of the impracticability of attempting to represent every anal- 

 ysis taken, and its relation to others in the same vein, I 

 have been obliged to select those analyses which represent av- 

 erages ; and in the vertical longitudinal sections of various 

 rooms the figures entered in the map represent average percent- 

 age in phosphorus of the ore in that particular place covered 

 by the figures, and in the plane through which section is made. 

 Fig. 19 gives the detail of various averages in 1 and 2 Rooms, 

 5 Shaft. While the ore left in the pillars has not been subjected 

 to analysis, I have for the sake of clearness drawn through 

 the pillars the isochemic lines indicated by the percentages in 

 phosphorus in the rooms which they support. Figure 23 is an 



